锂云母提锂一次净化渣制取硫酸铝的研究

【作者】 吴宋超；

【导师】 赖华生；

【作者基本信息】 江西理工大学 ， 冶金物理化学， 2011， 硕士

【摘要】 为从硫酸盐法锂云母提锂浸出液中制备合格的碳酸锂产品,必须对浸出液进行分步净化除杂。一次净化渣就是通过用CaO调节浸出液的pH值,使浸出液中的Al3+形成氢氧化物沉淀所获得的产物。该产物一次净化渣渣量大,富含大量的Al、Ca成分。如果直接排放堆置,则造成资源的浪费和环境的污染。因此考虑回收一次净化渣中的铝钙资源,即降低环境污染又能创造一定的经济价值。本课题用硫酸浸出法回收净化渣中的铝钙成分。提铝制备硫酸铝主产品,钙则以硫酸钙的沉淀形式回收返回锂云母生产碳酸锂的主流程循环利用。为制备合格的硫酸铝产品,针对净化渣物相及成分特性,选择焙烧水浸工艺预先处理净化渣,浸出净化渣中大量的碱金属元素。在水浸过程中,研究了焙烧温度、焙烧时间以及单因素研究了水浸温度,水浸液固比、水浸时间等对各碱金属元素浸出率的影响。在最佳焙烧水浸工艺条件下,锂浸出率达到82.30%,钠浸出率达到79.68%、钾浸出率达到83.95%、铷浸出率达到86.86%、铯浸出率达到81.23%。经过焙烧水浸碱金属元素后的净化渣改称铝钙渣。首先用硫酸单级浸出铝钙渣,试验研究了32～34%硫酸用量、酸浸温度、酸浸时间、液固比、搅拌强度等因素与铝浸出率的关系。实验结果表明,在最佳工艺条件下硫酸单级浸出铝钙渣工艺制备的硫酸铝溶液浓度不高,而且硫酸铝溶液中游离酸过高,需要消耗大量的碱来中和,成本加大。考虑上述硫酸单级浸出工艺存在的问题,改用三级逆流连续浸出工艺,在单级浸出工艺参数的基础上进行适当调整,得到适宜的工艺条件,在此条件下,铝浸出率高达98%,相比较单级浸出工艺,铝浸出率提高了的大约2%。硫酸铝溶液浓度也得到大幅度提高。在三级逆流浸出过程中需要解决的主要问题就是二级阶段和三级阶段的硫酸铝溶液的沉降问题,选用非离子型聚丙烯酰胺作为絮凝剂,研究探索絮凝剂的浓度和加入量对沉降效果的影响。确定出絮凝剂最佳浓度和用量。最后蒸发浓缩收集的硫酸铝溶液,控制好输出电压,当烧杯底部开始出现白色粉末状硫酸铝后即停止加热,自然冷却后,可获取硫酸铝产品,经过检测分析,制备的硫酸铝产品符合工业硫酸铝一级品的质量标准。更多还原

【Abstract】 For make qualified lithium carbonate from lifted lithium-leach liquor of lepidolite in sulfate, have to remove impurity step by step on leach liquor. First purification residue is production after formed hydroxide precipitates of Al3+ in leach liquor, by adjusting the pH of leach liquor by using CaO. This result is″residue″highly of first purification residue which is very high in Al and Ca, If the residue is discharged or piled up directly, it would be cause wasteful of resource and pollution of environment. Therefore, recovering the resource of aluminium and calcium in first purification residue is referenced, which not only reduces the environmental pollution but also has some economic value.This thesis recovers aluminium and calcium of purification residue by sulfuric acid leaching. Preparation main product of aluminum sulfate by abstracting aluminium, and calcium sulfate by precipitating calcium which return to main process flow of producing lithium carbonate for circulation utilization. For making a qualified product of aluminum sulfate, settling purification residue in advance is selected by means of roasting and water extraction which based on the phase characteristics and content of purification residue, the aim of that is leaching element of the alkali metal in purification residue. The factors that influenced leaching rate of element of the alkali metal are investigated during water extraction, including roasting temperature, roasting time, temperature, liquid-solid ratio and time of water extraction etc. Under the optimum conditions, leaching rate of lithium, sodium potassium, rubidium and cesium reaches 82.30%, 79.68%, 83.95%, 86.86% and 81.23% respectively.Purification residue after removing element of the alkali metal by roasting and water extraction is renamed aluminium-calcium residue. The relationship between leaching rate and factors is studied, which include the amount of sulfuric acid(32～34%), the temperature and time of acid extraction, liquid-solid ratio, stirring intensity etc in the process of single stage leaching aluminium-calcium residue by sulfuric acid. The results indicated that the concentration of aluminium sulphate solution is low in the optimum conditions which single stage extraction aluminium-calcium residue by sulfuric acid, and free acid content is higher in aluminium sulphate solution, that needs to use up a large number of alkali for counteracting and cost are enlarged.On the basis of the problems present in the single stage extraction, three stage upstream leaching is used instead. Adjusting technology parameters based on the single stage leaching to get appropriate conditions, in these conditions, the leaching rate of aluminium is as high as 98% which has a rise of 2% compared with single stage leaching, and the concentration of aluminium sulphate solution is raised substantially. Settlement of aluminium sulphate solution in the second and third stage is the major problem in the process of three stage upstream leaching. Influence of the concentration and amount of flocculant on settlement is studied when non-ionic polyacrylamide is selected for flocculant, and the best concentration and amount of flocculant are fixed.Finally, aluminium sulphate solution that have collected is used to evaporate, output voltage is controlled in this progress, removed from the heat when the white powder aluminium sulphate appeared in the bottom of the flask, the production of aluminium sulphate is obtained after being cooling naturally. The prepared aluminium sulphate measures up to the quality standard of grade-1 of the technical aluminium sulphate through detecting and analysis.更多还原